The use of adsorbents to remove SO2 from certain gas streams is known in the art. For instance, U.S. Pat. No. 5,358,701 describes a process for removing noxious sulphur oxides, nitrous oxides, and chlorine from gas streams, particularly from flue gases of coal-burning power plants, using layered double hydroxide (LDH) sorbents. The sorbents are particularly useful for SO2 absorption at temperatures in the range of 100° C. to less than 400° C. The SO2 gas absorbs into the hydrotalcite structure as SO32− anions by replacing most of the gallery CO32− anions. The adsorbed SO2 is driven-off by calcination at elevated temperatures (500° C.) and the LDH sorbents are regenerated by hydrolyzing the calcined product optionally in the presence of CO2 or CO32−.
Further, methods to fixate carbon dioxide are also known in the art. WO 2005/102916 for instance, describes apparatus and methods for converting hydrocarbon fuels to hydrogen-rich reformate that incorporate a carbon dioxide fixing mechanism into the initial hydrocarbon conversion process. The mechanism utilizes a carbon dioxide fixing material within the reforming catalyst bed to remove carbon dioxide from the reformate product. The removal of carbon dioxide from the product stream shifts the reforming reaction equilibrium toward higher hydrocarbon conversion with only small amounts of carbon oxides produced. Fixed carbon dioxide may be released by heating the catalyst bed to a calcination temperature. A non-uniform distribution of catalysts and carbon dioxide fixing material across catalyst bed yields higher conversion rates of hydrocarbon to hydrogen-rich reformate.
US 2004/081614 describes a process for producing a high temperature COx-lean product gas from a high temperature COx-containing feed gas, which includes providing a sorption enhanced reactor containing a first adsorbent, a shift catalyst and a second adsorbent; feeding into the reactor a feed gas containing H2, H2O, CO and CO2; contacting the feed gas with the first adsorbent to provide a CO2 depleted feed gas; contacting the CO2 depleted feed gas with the shift catalyst to form a product mixture comprising CO2 and H2; and contacting the product mixture with a mixture of second adsorbent and shift catalyst to produce the product gas, which contains at least 50 vol. % H2, and less than 5 combined vol. % of CO2 and CO. The adsorbent is a high temperature adsorbent for a Sorption Enhanced Reaction process, such as K2CO3 promoted hydrotalcites, modified layered double hydroxides, spinels, modified spinels, and magnesium oxides.
U.S. Pat. No. 6,322,612 describes a pressure or vacuum swing adsorption process and apparatus used for the separation and recovery of certain gaseous components, such as carbon dioxide from hot gas mixtures containing water vapour. The process comprises introducing the feed gas mixture at an elevated temperature into a feed end of an adsorber column containing an adsorbent. The adsorbent preferentially adsorbs at least one adsorbable component. An adsorber effluent, depleted of the at least one adsorbable component, is withdrawn from a product end of the adsorber column. The adsorber column is depressurized below atmospheric pressure and then purged with steam to withdraw an effluent comprising a mixture of the at least one adsorbable component and H2O. Next, the adsorber column is pressurized by introducing a gas that is depleted of the at least one adsorbable component. The steps are repeated in a cyclic manner.
Further, Descamps et al (Energy 33 (2008)874-881)) and Maurstad (8th International Conference on Greenhouse Gas Control Technology, Trondheim, 2006 (“Impact of coal quality and gasifier technology on IGCC performance” (Abstract)) describe the removal of CO2 and H2S from coal derived syngas, wherein in the former H2S is removed at ambient temperatures to provide a clean water gas shift (WGS) gas, followed by the WGS reaction in several reactors, and followed by CO2 removal at ambient temperatures, and wherein in the latter a sour-gas WGS is performed in several reactors, and wherein thereafter H2S and CO2 are removed at ambient temperatures.